A well system (e.g., oil or gas wells for extracting fluids from a subterranean formation) can include a drill rig. The drill rig can include a rotating control device (RCD). The RCD can divert fluid from the well system to specific well system equipment. The position of the RCD in the well system, however, can change depending on whether the drill rig is land-based or offshore, such as on a floating platform in the sea. For example, in a land-based drill rig, the RCD can be positioned at the well's surface. A well operator can directly connect or disconnect well components to the RCD. In an offshore drill rig, however, the RCD can be positioned in a less convenient location for the well operator. For example, the RCD can be positioned in a section of a riser that is below sea level. The riser can be a tube for transporting materials between a wellbore drilled into the seafloor and a well system component at the water's surface. In such situations, the RCD may not be easily accessible by the well operator.